Workaround github issue

Temporary revert aspiration window patch
so to be visible to everybody: it will be
re-applied with next patch

No functional change (together with next one)
Simplify aspiration window code

Here the main difference is that now we center
aspiration window on last returned score. This allows
to simplify handling of mate scores.

We have done a reversed SPRT tests, where we wanted to
verify if master is stronger than this patch.

Long TC: master vs this patch (reverse test)
LLR: -2.95 (-2.94,2.94)
Total: 37992 W: 7012 L: 6920 D: 24060

bench: 4507288
Reduce window when researching: d = 2

bench: 4560295
Merge branch 'master' into aspiration